1. Field of the Invention
The present invention relates to the technology field of high-quality light, and more particularly to a method for producing high-quality light.
2. Description of the Prior Art
Light is an important application in human civilization society. According to natural light emitted by sun, the ancient people are able to rise with the sunrise and take rest with the sunset. With the advancement of the technologies, the artificial light is developed from bulb to incandescent bulb after the Edison invents the bulb. Moreover, the solid-state lighting (SSL), such as light-emitting diode (LED), organic light-emitting diode (OLED) and polymer light-emitting diode (PLED), the latest lighting technology is further be proposed.
ELI (ergonomic lighting indicator) is a comprehensive evaluating standard for lighting quality. Please refer to FIG. 1, there is shown a degree indicator diagram of the ELI. As shown in FIG. 1, ELI includes 5 indicating indices for evaluating a light source, the indicating indices consists of:    (A) visual performance, including the factors of illumination, color rendering, and contrast;    (B) vista, including the factors of user psychology, visual hierarchy, and building materials;    (C) visual comfort, including the factors of light distribution uniformity, the existence of uncomfortable glare, and light flashes;    (D) vitality, including the factors of impacts on people's psychological and stimulation; and    (E) empowerment, including the factors of individual light modulation, selective lighting scenes and layouts.
Therefore, through above descriptions, it is able to know there have 4 indicating indices of the ELI being correspondent with the physiological perception of human, which are visual performance, vista, vitality, and empowerment. Accordingly, it is able to further understand that the human's physiological perception is very important for the ELI.
However, differing from the ELI, CRI (color rendering index) is used for evaluating the light quality by distinct way. The method for measuring the CRI of a light source includes the steps of: Firstly, making a light source to illuminate an object for facilitating the object reveals its object color; next, making a reference light source to illuminate the object for facilitating the object reveals a reference object color. Eventually, quantitatively comparing the object color with the reference object color according to 8 color samples of DIN 6169, therefore the CRI of the light source can be obtained.
Through the method steps for measuring the CRI of the light source, it is able to know that the primary step is comparing the object color with the reference object color according to 8 color samples of DIN 6169; obviously, the CRI-measuring steps does not concern or refer human's physiological perception. Based on this reason, predictably, the light source having high CRI value may not show good ELI values on visual performance, vista, vitality, and empowerment. It means that CRI may not be the best index for light source quality because of lacking fairness and consistency.
On the other hand, researchers have found that the production and the secretion of melatonin are mainly influenced by the following three factors:    (1) Light: light is transmitted to hypothalamus through retinal nerves, and then transmitted to pineal body through the sympathetic nerves, so as to inhibit the secretion of melatonin, therefore the secretion of melatonin can be inhibited in higher level under the darker environment.    (2) Circadian rhythm: hypothalamus, like a biological clock, can affect the secretion of melatonin, so that the concentration of melatonin secreted by pineal body has a significant variation according to circadian rhythm, and the concentration of melatonin in blood in the night is 6 times higher than that in the day according to researches.    (3) Electromagnetic wave: an electromagnetic wave can not only inhibit the ability of pineal body for synthesizing melatonin, but also inhibit the activity of the synthesis of melatonin.
Light is indispensable in daily life. The light perceivable by human eyes is called visible light, wherein the major natural light is sunlight, and the artificial light has various kinds, such as candlelight, incandescent lamps, fluorescent lamps, LED lamp, OLED lamps, etc. Generally speaking, the wavelength range of the visible light is about 450 nm to 750 nm; the color components of the visible light include red, orange, yellow, green, blue, purple, etc.
According to literatures, different color lights would cause different sensitivity to melatonin of human. Please refer to FIG. 2, which shows a diagram of curves representing relativity between light wavelengths and light sensitivity of melatonin. In FIG. 2, curve A represents a photopic luminosity function for the different color lights, and data group shows the light sensitivity caused by the different color lights to melatonin of human. Apparently, in FIG. 2, melatonin has a higher light sensitivity under the color lights having short wavelengths; on the contrary, melatonin has a lower light sensitivity under the color lights having long wavelengths. So that, naturally, for human beings, who are able to avoid melatonin from being suppressed by way of preventing the bodies thereof to be exposed under the light with short wavelength.
Although the data group in the FIG. 2 have proved that melatonin has a higher light sensitivity under the color lights with short wavelengths, literatures have not ever disclosed or recorded the following facts: As shown in FIG. 2, curve B represents melatonin suppression extent per lumen for quanta from different wavelengths. The curve B shows, of course, the quanta from short wavelength light caused higher suppression extent on melatonin under unit lumen; However, to man's surprise, the melatonin suppression extent caused by quanta from long wavelength (around 780 nm) is nearly equal to the melatonin suppression extent caused by quanta from short wavelength (around 480 nm).
According to above descriptions, the most important issue for research and development engineers of lighting products is how to produce a high-quality lighting product simultaneously giving the consideration to the sensitivity of human eyes and the melatonin suppression. In view of that, the inventors of the present application have made great efforts to make inventive research thereon and eventually provided a method for producing high-quality light.